Routine anaerobic culture of urine identified the urinary tract as the primary focus of sepsis in a postoperative patient with Bacteroides fragilis septicaemia. Specimens of urine from six other symptomatic patients grew > 10(8) cfu/litre of a Bacteroides species in pure growth. The significance of these isolates is discussed. Multipoint technology and the availability of anaerobic work stations have facilitated anaerobic culture and reduced its cost. The incorporation of anaerobic culture of urine into routine laboratory practice may be clinically valuable and should be considered.